CLOSED: Black body with yellow-orange tail - wasp/ hornet?

Tried to get some pictures, but cannot see them in any of the shots I took.

There must have been 50-60 of them flying low in an area about 15 feet in diameter under a tree - partial shade.
They appeared to be mating. They would land in the grass (St Augustine), then pop right back up.
Flight was mostly below 18 inches and much was 6 inches. They did not pay any attention to me, so no aggression.
And - they stayed at this for several hours.

I checked later in the afternoon and a few (maybe 4-6) were still in the area, but flew off when I walked into the area.

They did not look like the black mud daubers that inhabit the garage, but were about the same size - 2-2.5 inches long.

I have similiar flying insects and they do not look like any of the pics suggested. The abdomen is orange and the wings and head are black. They are low flying and are around from mid morning to mid afternoon. I can not find a nest, but am also not sure what I should be looking for since I do not know what it would look like. I will attempt to get a picture.